class for manipulating URL

MyURL.java

package org.saekiyoshiyasu.common;

/**
    Copyright: (c) SAEKI Yoshiyasu
    License  : MIT-style license
               <http://www.opensource.org/licenses/mit-license.php>
    last updated: 2012/03/16
**/

import java.net.URL;
import java.net.MalformedURLException;
import java.util.List;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.Collections;
import java.util.Comparator;
import java.util.Locale;

import org.saekiyoshiyasu.common.Pair;

/**
 * class for manuplating URL
 * Usage:
 *  MyURL url = new MyURL("http://user:pass@example.org:8888/cgi/foo.php?bar=1#head");
 */
public class MyURL {

    private String scheme = null;
    private String userinfo = null;
    private String host = null;
    private int port = -1;
    private String path = null;
    private List<Pair<String, String> > query = null;
    private String queryAsString = null;
    private String fragment = null;

    public MyURL(String url) throws MalformedURLException {
        URL basedURL = new URL(url);
        this.scheme = basedURL.getProtocol();
        this.userinfo = basedURL.getUserInfo();
        this.host = basedURL.getHost();
        this.port = basedURL.getPort();
        this.path = basedURL.getPath();
        this.queryAsString = basedURL.getQuery();
        this.query = splitPairs(queryAsString);
        this.fragment = basedURL.getRef();
    }

    public MyURL(URL url) throws MalformedURLException {
        this(url.toString());
    }

    public String toString() {
        String resultURL = scheme() + "://";
        if(userinfo() != null && ! "".equals(userinfo())) {
            resultURL += userinfo() + "@";
        }
        resultURL += host();
        if(port() > 0) {
            resultURL += ":" + port(); 
        }
        resultURL += path();
        if(queryAsString() != null && ! "".equals(queryAsString())) {
            resultURL += "?" + queryAsString();
        }
        if(fragment() != null && ! "".equals(fragment())) {
            resultURL += "#" + fragment();
        }
        try {
            URL url = new URL(resultURL);
        } catch(MalformedURLException murle) {
            murle.printStackTrace();
            System.err.println("URL generate error!");
            showElements();
            resultURL = null;
        }
        return resultURL;
    }

    public URL toURL() throws MalformedURLException {
        return new URL(toString());
    }

    public String scheme() { return scheme; }
    public String userinfo() { return userinfo; }
    public String host() { return host; }
    public int port() { return port; }
    public String path() { return path; }
    public List<Pair<String, String> > query() { return query; }
    public String queryAsString() { return queryAsString; }
    public String fragment() { return fragment; }

    public void setScheme(String scheme) { this.scheme = scheme; }
    public void setUserinfo(String userinfo) { this.userinfo = userinfo; }
    public void setHost(String host) { this.host = host; }
    public void setPort(int port) { this.port = port; }
    public void setPath(String path) { this.path = path; }
    public void setQuery(List<Pair<String, String> > query) {
        this.query = query;
        this.queryAsString = joinPairs(query);
    }
    public void setQueryAsString(String queryAsString) {
        this.queryAsString = queryAsString;
        this.query = splitPairs(queryAsString);
    }
    public void setQuery(String queryAsString) {
        this.queryAsString = queryAsString;
        this.query = splitPairs(queryAsString);
    }
    public void setFragment(String fragment) { this.fragment = fragment; }

    private void showElements() {
        System.err.println(
                String.format(
                    "Scheme: %s\nUserInfo: %s\nHost: %s\nPort: %d\nPath: %s\nQuery: %s\nFragment: %s",
                    scheme(), userinfo(), host(), port(), path(), queryAsString(), fragment()
                    ));
    }


    /**
     * if all components are same, these instances are same.
     */
    public boolean equals(Object obj) {
        if(obj == null)
            return false;
        if(! (obj instanceof MyURL))
            return false;
        MyURL uobj = (MyURL)obj;
        return (
            this.scheme() == null ? uobj.scheme() == null : this.scheme().equals(uobj.scheme()) &&
            this.userinfo() == null ? uobj.userinfo() == null : this.userinfo().equals(uobj.userinfo()) &&
            this.host() == null ? uobj.host() == null : this.host().equals(uobj.host()) &&
            this.port() == uobj.port() &&
            this.path() == null ? uobj.path() == null : this.path().equals(uobj.path()) &&
            this.queryAsString() == null ? uobj.queryAsString() == null : this.queryAsString().equals(uobj.queryAsString()) &&
            this.fragment() == null ? uobj.fragment() == null : this.fragment().equals(uobj.fragment())
          );
    }

    private List<Pair<String, String> > splitPairs(String allPairs) {
        if(allPairs != null && ! "".equals(allPairs)) {
            List<Pair<String, String> > pairList = new ArrayList<Pair<String, String> >();
            String[] pairs = allPairs.split("&");
            for(String pairString: pairs) {
                String[] tuple = pairString.split("=");
                String key = pairString;
                try {
                    key = tuple[0];
                } catch (ArrayIndexOutOfBoundsException aiobe) {
                    System.err.println(pairString + " is strange query.");
                }
                String value = null;
                if((! pairString.equals("=")) && pairString.contains("=")) {
                    value = "";
                }
                try {
                    value = tuple[1];
                } catch (ArrayIndexOutOfBoundsException aiobe) {
                    // System.err.println(key + " has no value.");
                }
                Pair<String, String> pair = new Pair<String, String>(key, value);
                pairList.add(pair);
            }
            return pairList;
        } else {
            return null;
        }
    }
    
    private String joinPairs(List<Pair<String, String> > pairList) {
        if(pairList != null) {
            StringBuffer pairsSB = new StringBuffer();
            Iterator<Pair<String, String> > iter = pairList.iterator();
            if(iter.hasNext()) {
                Pair<String, String> firstPair = iter.next();
                if(firstPair.second() == null) {
                    pairsSB.append(firstPair.first());
                } else {
                    pairsSB.append(firstPair.first() + "=" + firstPair.second());
                }
            }
            while(iter.hasNext()) {
                Pair<String, String> pair = iter.next();
                String key = pair.first();
                String value = pair.second();
                pairsSB.append("&");
                if(value == null) {
                    pairsSB.append(key);
                } else {
                    pairsSB.append(key + "=" + value);
                }
            }
            return pairsSB.toString();
        } else {
            return null;
        }
    }
}